JPH07125124A - Pp foam for stamping skin material and manufacture of the same - Google Patents

Abstract

PURPOSE:To make a skin material for stamping with high finishing precision by molding foam with a desired expansion ratio to a compressed state and to obtain the foam with a low rate of change of thickness. CONSTITUTION:Foam with a desired expansion ratio is molded to a compressed state; the rate of change of foam thickness is controlled to be 5% or less at 120-140 deg.C. For example, desired amounts of a crosslinking component such as triallyl cyanulate and divinylbenzene and a foaming agent such as ADCA are added to 100 pts.wt. of polypropylene as necessity requires. The mixture is expanded by electron beam crosslinking to make polypropylene foam having a desired expansion ratio and desired thickness; the foam is compressed by a desired means and contracted to desired thickness.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a PP foam for a stamping skin material and a method for producing the foam.

[0002]

2. Description of the Related Art Conventionally, this type of foam is only formed at a desired magnification, and a stamping skin material is formed by laminating a soft sheet such as a vinyl chloride sheet, a woven cloth or a non-woven cloth that has been subjected to a drawing process. It was what I had composed.

[0003]

However, since the above-mentioned conventional foams have a high rate of change in thickness, there is a high possibility that the surface of the stamping product (the surface of the soft sheet of the skin material) will have pockmarks (roughness). It was the cause of defective products.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to form a foaming material having a low thickness change rate, which constitutes a skin material for stamping having high finished accuracy of products. To provide
The purpose is to provide a method for producing the foam.

[0005]

In order to achieve the above object, the technical means of the present invention is to foam the material to a desired ratio and to form it in a compressed shape. Further, the thickness change rate of the foam material is 5% or less when heated at 120 ° C to 140 ° C.

The foam material is formed by heating and compressing it after forming it to a desired expansion ratio.

[0007]

EXAMPLE An example of the foam for stamping skin material of the present invention and the method for producing the foam will be described below. The foam is formed into a compressed shape while being foamed to a desired ratio, Stamping to form automobile interior materials, viewing chairs, cases, etc. by laminating desired soft sheets (vinyl chloride sheet, woven cloth, non-woven cloth, etc.) by any means such as adhesion processing (by desired adhesive) or lamination processing. It constitutes the skin material.

The foam is, for example, polypropylene (P
P) For 100 parts by weight, for example, a crosslinking component such as triallyl cyanurate, divinylbenzene, ethylene glycol dimethacrylate, and acrylic acrylate, and a desired amount of ADCA or the like as a foaming agent are added as necessary to perform electron beam crosslinking. The polypropylene foam (PPF) is foamed to have a desired expansion ratio and a desired thickness, and the polypropylene foam (PPF) is compressed by a desired means to be shrink-formed to a desired thickness. The above-mentioned cross-linking component and foaming agent are merely examples and are not limited in any way, and can be changed as appropriate, and the cross-linking component may be copolymerized with PP and is arbitrary. As the crosslinking method, peroxide crosslinking, other radiation crosslinking, or other known means is adopted.

Specifically, the rate of change of the foam thickness is 1
It is formed by compression so as to be 5% or less when heated at 20 ° C to 140 ° C, and if the thickness change rate is higher than 5%, the occurrence rate of pockmarks (surface roughness) and the like is unfavorably high. PP foam material (PPF) is, for example, Toray Pef 13030 (13 times foam, 3 mm, polypropylene foam), Toray Pef 15
030 (15 times foam, 3mm, polypropylene foam)
(Toray Industries, Inc.) and the like are used. If it is not less than 20 times the expansion ratio, it will melt or collapse during molding.

As the foaming agent, for example, azodicarboxylic acid amide is used, and the addition amount thereof is preferably 10 to 30 parts by weight with respect to 100 parts by weight of PP. If it is less than 10, the foaming will be insufficient, and if it is more than 30, excessive foaming will occur. The gel fraction needs to be 40% or more. This is because if it is 40% or less, there is a risk of melting or breaking during stamping molding.

Next, one example of the method for producing the PP foam of the present invention will be described. First, PP foam (PPF) is foam-molded to a thickness of 15 times and a thickness of 3 mm.

Then, the foamed PP foam (PPF) is heated and compressed by a desired means, for example, heated and rolled by a roll having a desired gap. Therefore, as a result, the PP foam of this embodiment in a contracted state is formed. In addition, in the heat compression step, the temperature of 130
It was carried out under various conditions such as ˜180 ° C., speed 5 m / min, etc., but this is only one example and can be changed appropriately.
Further, when the effect is insufficient, the above steps (heat compression step, and rolling step when residual heat is sufficient) may be repeated a plurality of times.

Therefore, since the foam having a constant thickness is always obtained through the above steps, the variation in the clearance at the time of stamping is reduced. The method for producing the PP foam is merely an example and is not limited thereto. For example, the foam formed by laminating a soft sheet on the foam and then heat-compressing the foam to form a contracted shape. May be changed appropriately.

In Table 1 below, the rate of change in thickness of the PP foams of the above-mentioned Examples is shown in comparison with Comparative Examples. In Comparative Example 1, PP foam after foaming (before compression formation) in this example (15 times foam 3 mm, before compression) was used.

[0015]

[Table 1]

Therefore, as shown in Table 1 above, the thickness change rate of this example in the range of 120 ° C. to 140 ° C. is 5% or less, and the difference is remarkable as compared with the comparative example. . In this example, only the foam was heated for the test, but the same test was performed for the foam in which the desired soft sheet was laminated and heated, and the result was the same as that of this example. Further, the soft sheet was tested using several types such as PVC sheet, woven cloth, non-woven cloth, etc., and all the same effects were obtained.

The bending stress of the PP foam of Example 1 and the PP foam of Comparative Example 1 were measured and are shown in comparison with Table 2 below. Further, in the figure, A indicates a test piece (PP foam), and B indicates a pressure test device for strograph. Although the results shown in Table 2 were obtained by using only the PP foam, the same remarkable difference was obtained even when the foam was laminated with the desired soft sheet as above.

[0018]

[Table 2]

[0019]

EFFECTS OF THE INVENTION The present invention has the above-described structure, and the thickness change rate of the foam is extremely low. Therefore, the stamping skin material patter (surface roughening) caused by the high rate of thickness change of the conventional foam is generated. ), Problems such as wrinkles and whitening have been resolved, and the defective product rate of stamping products has dropped significantly. Therefore, according to the present invention, it is possible to provide a stamping skin material having a high product finish accuracy.

Further, in the present invention, since the PP foam for the stamping skin material is formed by the method in which the foam is formed to the desired ratio and then the compression is formed, the PP foam having a small thickness change rate can be manufactured.

Further, a product obtained by stamping a skin material using the PP foam of the present invention needs to be subjected to edge treatment by bending the edges inward after stamping, but the PP foam of the present invention has the above-mentioned structure. Since the bending stress is small, bending work becomes easy, workability is good, and labor is reduced.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing a bending stress test.

[Explanation of symbols]

 A: Test piece (PP foam) B: Test device

Claims (3)

[Claims] 1. A PP foam for a stamping skin material, which is a foam forming a stamping skin material by laminating with a soft sheet, and is formed into a compressed shape while being foamed to a desired ratio. 2. A foam forming a stamping skin material by laminating with a soft sheet, the thickness change rate of which is 12.
PP foam for stamping skin material, which is 5% or less when heated at 0 ° C to 140 ° C. 3. A method for producing a PP foam for a stamping skin material, which comprises forming a foam to a desired expansion ratio and then heating and compressing the foam.